A poll of 400 people from Dobbs Ferry showed 260 preferred chocolate raspberry coffee while 180 out of 250 in Irvington preferred the same flavor. To test the hypothesis that there is no difference in preferences in the two villages, what is the alternate hypothesis?
A. pi 1 < pi 2
B. pi 1 > pi 2
C. pi 1 = pi 2
D. pi 1 does not = pi 2
If the 1% level of significance is used and the computed value of z is +4.00, what is our decision?
A. Do not reject H0
B. Reject H0
C. Reject H1
D. None of the above
What is the critical value for a one-tailed hypothesis test in which a null hypothesis is tested at the 5% level of significance based on a sample size of 24?
A. 1.708
B. 1.714
C. 2.060
D. 2.064
A manufacturer wants to increase the shelf life of a line of cake mixes. Past records indicate that the average shelf life of the mix is 216 days. After a revised mix has been developed, a sample of nine boxes of cake mix gave these shelf lives (in days): 215, 217, 218, 219, 216, 219, 217, 220 and 218. At the 0.025 level, has the shelf life of the cake mix increased?
A. No, because computed t lies in the region of acceptance.
B. No, because 217.24 is quite close to 216.
C. Yes, because computed t is greater than the critical value.
D. Yes, because computed t is less than the critical value.
Thank you
